Polyglycerols are widely used in food and cosmetic industry. Generally, polyglycerols produced at elevated temperature (250-270° C.) are highly colored and due to aesthetic reasons, polyglycerols require color reduction treatment before they can be used.
Conventional methods of reducing color in polyglycerols are by adsorption of the color producing substances on an adsorbent material. Acid-activated bleaching earth or clay, sometimes called bentonite, is the adsorbent material that has been used most extensively. This substance consists primarily of hydrated aluminum silicate. Anhydrous silica gel and activated carbon are also used as a reducing color adsorbent to a limited extent.
However, this adsorbent adsorbs and traps within itself a weight of oil approximately equal to its own weight. Thus, a higher volume of adsorbent is required during the reducing color operation. Further, more oils have to be reclaimed from the spent adsorbent or are lost from processing stream in spent adsorbent, which is discarded. Hence, a process which requires less amount of adsorbent and which increases adsorbent usage efficiency, are highly desirable.